Several problems are associated with extended idling periods of EPA Tier IV diesel engines in construction equipment or heavy equipment. Exhaust after treatment systems, such as those used to meet EPA Tier IV emission requirements, are designed to function at normal engine operating speed and typical load with relatively short periods of no load idling. At normal engine operating speed and typical load, pollutant emissions in the diesel engine exhaust being introduced to the exhaust after treatment system are significantly lower than at idle and no load. This is primarily due to the lower exhaust gas temperature of the idling, no load engine, which does not burn up as many of the pollutants before introduction of the exhaust gas to the after treatment system. However, on job sites in very cold climates and with no access to electrical power for operating devices like engine coolant heaters or engine oil heaters, the typical method used to guarantee a diesel engine powered piece of construction equipment would be operational at the beginning of the work day is to let the large diesel engine of the heavy equipment idle overnight. This solution to the cold climate starting problem causes the accumulation of excessive operating hours on the construction equipment, the consumption of significant quantities of diesel fuel, and the constant release of excessive amounts of environmentally damaging diesel exhaust gases into the atmosphere. Moreover, operating an engine, such as one regulated as an EPA Tier IV engine, at idle with no load for extended periods, such as overnight periods, causes the exhaust after treatment system to fail over time and the engine to shut down until repairs are made.
Additionally, hydraulic excavator required support functions of an oil or gas well drilling operation present additional problems. As a drill rig creates the well hole, drilling solution is pumped into the hole. A slurry mixture of drilling solution and drilled particulate material is pumped out of the well hole. After removal from the well hole, this slurry mixture is processed to reclaim most of the drilling solution. The remaining material is dumped into a large, high sided, open topped hopper. After a sufficient volume of material is placed into the hopper, a solidifying agent such as clay, sand, or straw is added to the material using a hydraulic excavator. The hydraulic excavator is then used to mix the solidifying agent with the material to create a semi-solid material which can be accepted by a landfill. After mixing is complete, the hydraulic excavator is additionally used to load the material from the hopper into dump trucks. Once the drilling process begins, the drill rig runs 24 hours per day, 7 days per week until the well is finished. Job requirements mandate that the supporting hydraulic excavator be on site warmed up, fully functional, and ready to work with an operator standing by the entire time the drill rig is running. The nature of the drilling process is such that 4 to 6 hours may pass before a sufficient volume of material is placed in the hopper to require mixing and removal by the hydraulic excavator. The mixing and removal process can typically be completed in approximately 2 hours. As such, in a 24 hour period, the hydraulic excavator will only be working 6 to 8 hours. Since the hydraulic excavator and operator are required to be in a state of constant readiness at all times the drill rig is running, the hydraulic excavator is left idling at no load for 16 to 18 hours out of 24 in order to keep the diesel engine and hydraulic system up to operating temperature and to provide climate control and auxiliary power to the operator. This mode of operations accumulates excessive operating hours on the construction equipment and consumes significant quantities of diesel fuel. The mixing and removal process is further complicated by the height of the hopper sides relative to the height of the operator in the cab of the hydraulic excavator. A conventional hydraulic excavator of appropriate size for this task does not elevate the operator high enough to have adequate visibility inside the hopper for the mixing and removal process.
Therefore, problems exist relating to equipment system readiness and avoiding cold starting a piece of heavy equipment, such as the accumulation of excessive operating hours on the construction equipment, the consumption of significant quantities of diesel fuel, the excessive release of exhaust gases, and the failure of exhaust after treatment systems. Additionally, the tasks required by an excavator on a job site present additional problems, such as inadequate visibility for a mixing and removal process. The auxiliary power unit excavator system of the present disclosure provides a solution to all of these problems.